May 6, 2020

expert reaction to comments made by the Boris Johnson at PMQs that he aims to reach 200,000 tests a day by end of May and higher after

During Prime Ministers Questions on the 6th May, The Prime Minister announced that the new target for testing is 200,000 a day bey the end of May. 

Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

“Unless there is an indication about how this extra testing capacity will be deployed its very difficult to make any judgement. It has already been a struggle to reach the current capacity and it is not entirely clear how well that testing system is really working.

“There will need to be extensive community testing and infection control measures, including effective and timely contact tracing, when we come out of lockdown if we are to prevent a resurgence in case numbers and all the problems that will bring to the NHS and the economy, but how these elements will fit together and how they will be coordinated and deployed is less than certain, at least it is not that clear to me.”

Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology, University of Edinburgh, said:

“The UK government is right to be focussed on testing, but it is very simplistic to focus simply on the numbers of tests.

“Testing is a tool, and what matters is how we use the tool. What is the strategy and how does testing help to deliver it?

“There are three ways in which we use tests for the presence of virus.

“One way is to confirm true positives – people who think they are infected and are. This is just standard clinical diagnosis, and plays a role in clinical care and case management.

“Another way is to test for false positives – people who think they may be infected but are not. This is the ‘back to work’ test. It plays a useful role but, because such people should already be self-isolating, it does not help suppress transmission.

“The final way is to test for false negatives – people who are not aware they are infected but are. This use of testing – screening –  is the one that helps bring down transmission rates. That is because it tells people – including, critically, those with pre-symptomatic infections – that they should self-isolate to protect others. The benefits of screening are far greater if the test is very sensitive (so detects infection well before the person becomes infectious) and/or is rapid. If test results are not available until after symptoms appear then – in terms of suppressing transmission – little is gained as the person should already be self-isolating.

“So it is not just about numbers; for screening to suppress transmission speed is equally important. Ideally, we need test results in hours, not days. More focus on speed of results would be welcome.”

Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:

“This week the Royal Statistical Society’s COVID-19 Taskforce issued a statement on the reporting of results from UK’s home-swab-test-kit operation: https://rss.org.uk/RSS/media/File-library/Policy/RSS-statement-reporting-results-from-home-swab-test-Kits_final.pdf.

“Counting kits out is not at all the same as reporting-back on the positive rate found from the kits that were not only issued but were used, returned to the test laboratory and analysed. Helpfully, we hope, the Taskforce suggests a reporting format by which to report the results from the initial 40,000 home-swab-test-kits that were famously issued on 1 May 2020. Victory Day might be just the day to celebrate not only the launch of, but also the first results from, this efficient UK operation.”

All our previous output on this subject can be seen at this weblink: www.sciencemediacentre.org/tag/covid-19

Declared interests

Prof Sheila Bird: SMB is a member of the Royal Statistical Society’sCOVID-19 Taskforce.

None others received.